Pulse modulation is a modulation method for generating a signal by changing a pulse. For example, pulse density modulation (PDM) generates a waveform based on density and sign (e.g., a plus, minus sign) of a pulse having a certain width. As another example, pulse width modulation (PWM) generates a waveform based on a width and a sign of a variable pulse.
In connection with these techniques, techniques related to a PWM-based D-class amplifier have been disclosed. In addition, techniques related to a multi-bit PDM signal gain adjustment circuit have been disclosed. Further, PWM modulators capable of improving a resolution and a dynamic range have been disclosed.